Time marker generator



3 31, 1955 N. G. KABuss ETAL 2,709,759

TIME MARKER GENERATOR Filed Feb. 9, 1953 BIAS 2 I :Z SOURCE OUTPUT FIG.I

PHASE SHIFT NETWORK INVENTORS NORBERT G. KABUSS WALTER H HIGA BY HUGO H.WOERDEMANN ATTORNEY TllVlE MARKER GENERATOR Norbert G. Kabuss, MontereyPark, Walter H. Higa, Pasadena, and Hugo H. Woerdemann, Torrance,Califi, assiguors to North American Aviation, Inc.

Application February 9, 1953, Serial No. 335,722

3 Claims. (Cl. 307-106) This invention relates to a magnetic timingdevice, and in particular to means for providing time markers on acathode ray tube sweep without the use of vacuum tubes.

The sweep on the cathode ray tube of a radar receiver is synchronized ata frequency which is a multiple of the frequency of the alternatingcurrent power source which supplies the receiver. At submultiples of thesweep frequency it is required to provide markers consisting of veryshort time duration pulses which show as lines or pips perpendicular tothe time base of the receiver presentation. In the past, this functionhas been performed by the use of vacuum tubes. This inventioncontemplates a time marker generator utilizing no vacuum tubes orcrystal devices, with only capacitors and magnetic components.

It is therefore an object of this invention to provide a time markergenerator of improved reliability.

It is another object of this invention to provide a time markergenerator involving the use of no vacuum tubes.

It is another object of this invention to provide a time markergenerator of increased accuracy.

Other objects of invention will become apparent from the followingdescription taken in connection with the accompanying drawings, in whichFig. 1 is a circuit diagram of the invention;

And Fig. 2 is a circuit diagram of a somewhat modified form of theinvention.

Referring to the drawings, and in particular to Fig. l, alternatingcurrent is supplied from source 1 to saturable core reactor 2 throughisolating inductance 3 and primary windings 4 and 5 of transformers 6and 7. Transformers 6 and 7 are preferably wound on special corematerial such as Deltamax or some other special material chosen for itsmagnetic properties. The capacitor 8 is connected in parallel with thesaturable reactor as shown. Secondary windings 9 and 10 of transformers6 and 7 are in turn connected to primary 11 of transformer 12, whilebias windings 13 and 14 of transformers 6 and 7 are supplied by biassource 15. Output from the device is taken from secondary winding 16 oftransformer 12, while bias is supplied from bias source 17 to biaswinding 18 of transformer 12.

Saturable reactor 2 is designed with a firing voltage such that it firestwice for each cycle of source 1, i. e., it fires once during thepositive going half cycle of source 1 and once during the negative goingcycle of source 1. The width of the resulting pulses is governed by thesize of capacitor 8. This pulse is conducted to primary windings 4 and 5of transformers 6 and 7 which are biased in opposite directions so thatwhile one is sensitive to positive pulses the other is sensitive tonegative pulses. Biasing is accomplished by means of windings 13 and 14connected as shown to bias source which supplies direct current. All thevarious bias windings shown are determined by the amount of bias currentavailable. The associated cores must be biased to saturation. Secondarywindings 9 and 10 of transformers 6 and 7 are connected in an additivesense to primary 11 of transformer 12 nitcd States Patent 0 2,709,759 lcPatented May-'51,

which is biased to cut off overshoot due' to dilferentiation intransformers 6 and 7. The output is taken from secondary winding 16 oftransformer 12 and consists of either positive or negative pulses spacedat twice the frequency of alternating current source 1. With thearrangement of the device shown in Fig. 1, two pulses are produced foreach cycle of the supply frequency.

If a larger number of pulses per cycle of the supply frequency isrequired, a circuit based upon the arrangement shown in Fig. 2 may beutilized. In Fig. 2 alternating current source 19 supplies alternatingcurrent through isolating inductance 20 to saturable reactor 21 andthrough phase shift network 22 to saturable reactor 23. Capacitors 24and 25 complete the input circuit as shown. Primary windings 26 and 27of transformers 28 and 29 are connected at one end to alternatingcurrent source 19 and at the other to the junction between saturablereactors 21 and 23. The secondary windings 30 and 31 of transformers 28and 29 supply current to the primary winding 32 of transformer 33, thesecondary of which supplies the output of the device. Bias to windings34, 35, and 36 is furnished by source 37. In this embodiment of theinvention a phase shift network 22 is utilized to shift the firing pointof saturable reactor 23 away from that of saturable reactor 21. Each ofthe saturable reactors still fires twice during each cycle of source 19,but if phase shift network 22 supplies a phase shift, for example, theresulting wave form supplied by transformer primary windings 26 and 27consists of two positive pulses 90 displaced and two negative pulses 90displaced. In this case, the two sets of pulses are also separated by90. Of course, the phase shift need not be 90, but may be less than 90,for example, 60; and additional saturable reactors may be employed sothat separation of the sets of pulses may be 60, 45, 30, or any numberof degrees referred to the cycle of source 19. As in the case shown inFig. 1, the Width of the pulses is determined by the size of capacitors24 and 25, and the functioning of transformers 28, 29, and 33 is similarto the functioning of transformers 6, 7, and 12 shown in Fig. l. Biassource 37 supplies bias both to bias windings 34 and 35 of transformers28 and 29, and to bias winding 36 of transformer 33.

There is thus provided a circuit useful in connection with radar forobtaining accurate time markings upon a cathode ray oscilloscope. Thecircuit involves the use of no vacuum tubes and hence is of indefinitelylong life and is highly dependable.

We claim:

1. Means for generating short duration electrical pulses comprising inseries and in order a source of alternating current, an isolatinginductance, a saturable core reactor, and a load impedance, and acapacitor connected from the source side of said load impedance to thesaturable reactor side of said inductance to thereby supply electricalpulses to said load impedance of duration determined by said capacitor.

2. A device as recited in claim 1 in which said load impedance comprisesthe primary windings of two transformers the secondaries of which areconnected in additive fashion, and further comprising means for biasingsaid transformers to thereby produce unipolar pulses at the output ofsaid transformers.

3. Means for producing unipolar electrical pulses of short durationcomprising a pair of current transformers having their primariesconnected in series, a source of alternating current connected at oneterminal to said transformer primaries, an isolating inductance, and asaturable core reactor connecting the other terminal of said alternatingcurrent source to the unconnected terminal of said transformer primarywindings, a capacitor connected between the saturable reactor side ofsaid iso- 3 4 lating inductance and the alternating current source sideduration electrical pulses at predetermined uniform inof saidtransformer primaries, a third transformer having lvalslts pr marywlndmg connected to the secondary Wmdmgs Refflences Cited in the file ofthis patent of sa1d pan of transformers, and means for predeterminatelybiasing said transformers whereby the secondary 5 UNITED STATES PATENTSwinding of said third transformer produces unipolar short 2,436,395Manley et a1 Feb. 24, 1948

